Reduction of acid consumption in alkylation



% ra so Feb. 16, 1965 E. A. KELSO 3,170,002

REDUCTION OF ACID CONSUMPTION IN ALKYLATION Filed June 19, 1965 2 Sheets-Sheet 2 PURE C 's l 88 PURE C 2.8% Cyclopentene HOURS OPERATION FIG. 3.

7ZPLANT 6 \llih H ADDITION H 50 CONCENTRATION WT.% w

3 .5 IO I5 3d TIME, HOURS ENTOR INV FIG.2.

EDWARD A. KELSO,

i satisfactory.

about'ltmah 1 The space velocity'of the olefin may rangeiror'n about 0.05'to about 3.0 volumes of olefin per volume of acid per antenna uunuc'rionl or Acin C(BNSEUMPTWN KN atnrrarron Edward "A. Keiso, Baytowra Tern, assign-or, by mesne v assignments, to Essolltesearchand Engineering Company, Elizabeth, N..F., a corporation of Deiaware Filed .Fune 19, 19%, See. No. 239,1193

' 21 Claims. (6!. Edit-63359) The present invention is directed to sulfuric acid alk-ylation. More particularly,the invention is concerned with reduction of acid consumption in sulfuric acid alkylation of an isoparafiin with an olefin. In its more specific aspects, the invention is concerned with the decreasing of acid consumption in sulfuric acid catalyzed alylation wherein a contaminated monoolefin is employed.

The present'invention may be briefly described as a.

methodof decreasing acid consumption in the sulfuric acid catalyzed alkylation of an isoparafiin with a mono- .olefinfraction contaminated with a smallamount t contarninants, including diolefin and cycloolefin, wherein the cycloolefin is selectively removed from the monoolefin. The isoparafiin is then alkylated with the cycloolefinffree ,presencebt a small amount of use hydrogen effective to overcome the effect or the diolefin on acid consumption.

United States Patent .0

monoolefin fraction under alkylation conditions in the a The present invention also involves decreasing acid con- 1 sumption in sulfuric acid catalyzed alkylation wherein the alkylation reaction isconjducted in the presence of a small amount of free hydrogen sutlicient to overcome the deleterious effects of diolefin in the olefin feed.

I The present invention also involves decreasing acid consumption'in the sulfuric acid catalyzed alkylation of an isoparaffin with a monoolefin fractionv contaminated with a small amount of 'cycloolefins wherein the cy'cloolefin is removed prior to-alkylation. The cycloolefin may" be removed by distillation of the mono-olefin fraction or by selective solvent extraction of the monoolefin fraction. p

Temperatures, employed in the alkylatiorimayfsuitably range from about 0 F. .to' about 100 .1 with a pre- I ferred'temperat'ure in the range from about 20 R about 60 F.'

' 1 it Pressures may range-from about Q 'toabout p.s.i.'g.

sufilcient to maintain the reactants in liquid phase. Pressures in the range from about'S to about 25, p.s.1.g. are

The'sulfuric acid may have a'fstrength from about 88 to aboutf99 percent by weight H 80 with a preferred H 80 concentration from about 195 to about 98 percent by Weight.

.Thei enternalweight ratio of isoparafiinltoolefin may] range from-about 1:1-to about 10:'1, with a preferred external ratiofrorr'i about 2:1 to about-5:1. The internal isoparafiinaolefin" ratio may range fromabout 10:1 to

about'1010O:1, with a preferred range of about 15;l -to ;:1:'

hour.

'suchas-lpropyleneg butenes,: pentenes, andheXenes, with butenes and pentenes'beingpreferred. s

The isoparaflins may suitably be the C to C iso paraffins, such as isobutane, isopentane, isohexane, isoheptane,

denser 39 which liquefies the withdrawn: reactants. The withdrawn liquefied reactants are dischargedinto an acand isooctane, with-the isobutane and isopentane being preferred. i

The amount of hydrogen employed on a molar'basis grangeifromabout 1:1 to about ltl: l to the diolefin content Where a solvent is employed is remove selectively isat least anequal molar basis to the dioelefin and may i through a shaft. 7 provided with internal bafiles 35- bet w'eenwhich the stirring devices 34 areilocated. 'The lastj two sections of the alkylatio'nreactionrzone are provided for acid and product withdrawal: The alkylate is" withdrawn;. from' .alkylation'reaction Zone '12- by line 36 for furtheritreata t V so The monooelfin may suitably be a C 'to C monoolefin,

' Patented Feb. 16,19 5

cycloolefins from the monoolefin fraction, solvents such as phenol, furfural, sulfur dioxide, diand tri-etliylen'e glycol, sultolane, abutyrolactone and the like may be used.

Solvent extraction may be conducted at temperatures Within the range from about-50 F. to about +200 F.

and a solvent to monoolefin ratio fro'm about 0.5 to about 20 may be employed.- r

The present invention will be further illustrated by ref erence to the drawing. in which FIG. I is a flow diagram of a preferred mode;

FIG. 2 is a plot of data showing the relationship be tween acid strength and hours operationwith the present invention; and

FIG; 3 is another plot of data showing the relationship betweenacid strength and hours operationfor another mode of the present invention. t T

.Referring now to the drawing and parti ularly to FIG. 1, numeral 11 designates a charge line by way of which a monoolefin feed is introduced into'the system for discharging into an alkylation reaction zone.12 through a manifold 13, controlled by valves 14, 15, and 16.

' In one aspect of the present invention, valve 17 in line 11 may be closedv and valve. 18 in branch line 19a may also be closed on an olefinic feed, such as C monoolefin feed, introduced into the system by line19, controlledby valve 2%. The'pentylenes fraction isintroduced by line 19 intoa fractional distillationzone 21 provided with suitable internal. bathing equipment or packing .for prey" cisefractional distillation.v Zone .21 isprovided with a heating meanaasuch as steam coil 22, line 23 for. re.-

moval' of an overhead fraction, and linefl24 for discharge of cyclopentene and heavier hydrocarbons. 1 The pentylenes are discharged by line:23 into line'll. in admixture with free hydrogen introduced by line 25, controlled by valve 26', and then introducediinto alkylation reaction zone- 12 through manlfold 13. Sulfuric acid is alsointroduced into zone 12 by line 27, 'control led by .valve' 28.; This acid mayflcomprise fresh sulfuric acid and recycle. sulfuric acid withdrawn from' zone 12 byline 29, controlled i byvalve 3-0, whichfl willinclude acid emulsifie'dinfhydrd carbon reactants. A portion of the acid gwithdrawni'by' line 29 maybediscarded tomaintainfacid strength. I 7 Also introduced into reaction zone121is isoparaifin feed, such as isobutane; which is introduced by line 31, controlled by valve 32. This isoparatfin war e ds recycled isopa'rafi in, such as isobutane -frorn line 33-, the source of which will be described hereinaiteri 7N lkylation reaction-zone ,12 is provided with a plufalliyDf; stirring devices 3% comprised ofv 'a prop eller actuated by a prime mover, suchfas an electric rnotor, Alkylation reaction zone 12 also. is

merit as will be described. v I I The reaction temperature may be maintained in reaction zonelZ by'withdrawingvaporized reactants by way of line 37 containing a compressor 38 and a 'co olercoincumulation zone-40 from whence propane-1 and lighter gases'may be discharged by line iLcontrolled by valve tion gives good results. The spent caustic solution is discharged from zone 43 by line 46, controlled by valve 47. The caustic washed alkylate is discharged from zone 43 by line 48 into a water-wash zone 49 into which water is introduced by line 50, controlled by valve 51.

Wash water is discharged from zone 49 by line 52,

controlledby valve 53. Y

The caustic and water-washed alkylate is then intro duced by line 54 into a distillation zone 55 which is vequipped similarly to distillation zone 21 with respect to internal vapor-liquid contacting means. Zone 55 is provided with a heating means, such as steam coil 56, line 57'for removal of an overhead fraction, line 58 for removal of a side stream butane fraction, and lines 59 and iL'COIlll'Ollfid, respectively, by valves or and 62, for withdrawal of alkylate fractions. Ieavy alkylate is discharged by line 63. Zone 55 may comprise a plurality of distillation towers with isobutane, normal butane,

and light alkylate recovered as overhead fractions.

The overhead fraction withdrawn by line 57 is predominately isobutane and is introduced through a condenser-cooler 64 into an accumulation zone 65 for recycle by way of line 65 to line 33 for return to the alkylation reactor 12.

In the practice of the present invention it is contemplated that the olefinic feed may be introduced directly to reaction zone 12 by line 11 or through branch line 19a to line 19 or the feed fraction may be introduced directly by line 19 into distillation zone 21. In the situations where the olefinic feed does not contain cycloolefins,

feed may be charged by line 11 directly to reaction zone 12, but if the feed contains cycloolefins, such as cyclo- -pentene, it will be charged to distillation zone 21. Part of the isoparaifin feed may also be added to the olefin feed prior to charging to the mixing zones of reactor 12.

, In the situations where the olefinic feed contains cycloolefins and acyclicand cyclic-diolefins, the cycloolefins will be removed and hydrogen will be employed as has been described.

It is contemplated that instead of a distillation zone 21, a solvent extraction zone, alone or in combination with a distillation zone, may be used to remove the cycloolefins. Preferably, a distillation zone will be em ployed. g g

By virtue ofemploying a 'method such as described with respect to FIG. 1, it is possible to reduce acid con- 'sumption remarkably by removing substantially cycloolefinsran d by charging hydrogen with the olefinic feed p in quality of the In order to illustrate the present invention, a number of sulfuric acid catalyzed alkylation' reactions were made with a commercial C monoolefin fraction from a sulfuric acid alkylation plant which contained 0.8% by wt. dienes and with runs wherein free hydrogen was added to the alkylation reactor in accordance with the invention using the same feed containing 0.8% dienes. I

The compositions of the acyclic olefin portion of all the feeds were essentially the same. The results of these operations are presented in FIG. 2. i

Referring to FIG. 2, it will be seen that with the plant pentene fraction containing 0.8% by Weight of dienes, the acid strength had declined to about 87% H 80 after about 45 hours; whereas, when hydrogen was added to the alkylation reactor, an acid strength of 87% H 80 was reached at approximately 56 hours. In short, in accordance with the present invention, hydrocarbon reactants containing contaminants such as dienes and the like are treated in situ with free hydrogen in contact with sulfuric or other acid catalyst, thus eliminating the need for a pretreatment operation.

Referring now to FIG. 3, runs are presented with a pure pentene fraction and a pure pentene fraction containing 2.8% by volume of cyclopentene. It will be noted by reference to FIG. 3 that at 100 hours the acid strength for the pentene fraction had declined to 86.5% H 80 whereas, when cyclopentene was present, the acid strength declined to 87.2% H 80 at 45 hours operation.

The alkylation runs illustrating the effect contaminants have on H 50 catalyst consumption and alkylate quality, as stated above, were made using pentenes as the olefin and isobutane as the isoparaflin under the following alkylation conditions:

Temperature, F. 45 Pressure, p.s.i.g Vol. percent H in emulsion 60 Isohutane: olefin ratio 5.1 Vol. olefin per vol. of acid/hour 0.12

[he results of these runs, which also are shown in FIGS. 2 and 3, are presented on a different basis in the following table:

7 1 0 alkylate yield was 1.5-1.6 gallon per gallon of olefin containing 86% light allrylate.

'Multioly by 13 to give pounds of 98% HZSOl consumption per gallon of olefin.

I From the data in the foregoing table, it is evident that the practice ofthe present invention allows the obtaining of results substantially identical to those obtained where a diolefin-free feedstock was used. Also, it is evident that cyclopentene contributes markedly to deterioration product and. in increased acid consumption.

It will be seen from the foregoing data that substantial improvements are obtained by introducing hydrogen into the sulfuric acid reaction zone with the olefin and by re moving cyclopentenes from the feed. 1

It'has been found in the practice of the present invention with a. refinery C olefin feed, one-fifth of the excess acid consumption when pentenes are alkylated as compared to butylenes is due to the'presence of dienes, and four-fifths'of the excess acid consumption is due to the presence of cyclopcntene. In this particular instance, the feed contained 0.8% dienes and 1.8% cyclopentenes.

While the invention has been described and illustrated with respect to H 50 catalyzed alkylation, the invention is also applicable to other acid catalyzed reactions such as those employing AlCl other Frledel-Crafts catalysts such as AlBr chlorosulfonic acid and fiuorosulfonic acid, and the like. Generally speaking, the invention is applicable to operations where the presence of diolefins and/ or cycloolefins is deleterious to the catalytic reaction;

The nature and objects of the present invention having been completely described and illustrated and the best mode contemplated in carrying out the invention set forth, what I wish to claim as new and useful and secure by Letters Patent is:

1. A method of decreasing acid consumption in the sulfuric acid catalyzed aikylation of an isoparaflin with a monoolefin contaminated with a small amount of a alkylation conditions in the presence of a small amount of free hydrogen eitective to overcome the effect of said diolefin on acid consumption.

2. A method in accordance with claim 1 in which the hydrogen is employed in an equal molar basis to the amount of diolefin.

3. A method in accordance with claim 1 in which the molar ratio of hydrogen to diolefin is from about 1:1 to about 10:1.

4. A method of decreasing acid consumption in the sulfuric acid catalyzed alkylation of an isoparafiln having 4 to 8 carbon atoms in the molecule with a C to C monolefin contaminated with a small amount of a diolefin which comprises conducting said alkylation under alkylation conditions in the presence of a small amountof free hydrogen effective to overcome the effect of said diolefin on acid consumption 5. A method in accordance with claim 4 in which the isoparafiin is isobutane and the monoolefin is a 0., fraction.

6. A method in accordance with claim 4 in which the isoparafiin is isobutane and the monoolefin is a C fraction.

7. A method of. decreasing acid consumption in the sulfuric acid catalyzed alkylat'ion of an isoparailm with a C monoolefin fraction contaminated with a small amount of cyclopentene which comprises substantially removing cyclopentene from said C monoolefin and then alkylating said isoparaffin with said C monoolefin substantially free of cyclopentene.

8. A method in accordance with claim 7 in which the cyclopentene is removed by distillation of said C fraction.

9. A method in accordance with claim 7 in which the cyclopentene is removed by extraction of said C fraction with a solvent selective for removal of said cyclopentcne.

10. A method of decreasing acid consumption in the sulfuric acid catalyzed alkylation of an isoparafiin with a monoolefin fraction contaminated with a small amount of contaminants including diolefin and cycloolefin which comprises substantially selectively removing cycloolefin from said monoolefin fraction and then alkylating said isoparafiin with said substantially cycloolefin-free monoolefin fraction under alkylation conditions in the presence of a small amount of free hydrogen effective to overcome the effect of said diolefin on acid consumption.

11. A method in accordance with claim 10 in which the hydrogen is employed in an equal molar basis to the amount of diolefin.

12. A method in accordance with claim 10 in which the molar ratio of hydrogen to diolefin is from about 1:1 to about 10:1.

13. A method in accordance with claim 10 in which the cycloolefin is removed by distillation of said monoolefin fraction.

I diolefin which comprises conducting said alkylation under with sulfuric acid in the presence of a small amount of free hydrogen effective to overcome the contaminating effect of said diolefin.

16. A method in accordance with claim 15 in which the hydrocarbon fraction is a monoolefin fraction hav' ing 3 to 6 carbon atoms in the molecule.

17. A method of treating a hydrocarbon fraction contaminated with a contaminating amount of a diolefin which comprises contacting said hydrocarbon fraction with an acid catalyst selected from the group consisting of sulfuric acid, chlorosulfonic acid, fiuorosulfonic acid, aluminum chloride, and aluminum bromide in the presence of a small amount of free hydrogen efliective to overcome the contaminating effect of said diolefin.

18. A method in accordance with claim 17 in which the hydrocarbon fraction is a monoolefin fraction having 3 to 6 carbon atoms in the molecule.

19. A method of treating a hydrocarbon fraction contaminated with a contaminating amount of an olefinic hydrocarbon. selected from the group consisting of diolefins and cycloolefins which comprises contacting said hydrocarbon fraction with sulfuric acid in the presence of a small amount of free hydrogen effective to overcome the contaminating eilect of said olefinic hydrocarbon.

20. A method of treating a hydrocarbon fraction contaminated with a contaminating amount of an olefinic hydrocarbon selected from the group'consisting of diolefins and cycloolefins which comprises contacting said hydrocarbon fraction with an acid catalyst selected from the group consisting of sulfuric acid, chlorosulfonic acid, fluorosulfonic acid, aluminum chloride, and aluminum bromide in the presence of a small amount of free hydrogen eifective to overcome the contaminating efiect of said olefinic hydrocarbon.

21. A method of decreasing acid catalyst consumption in the acid catalyzed alkylation of an isoparafiin with a monoolefin contaminated with a small amount of a diolefin which comprises conducting said alkylation under alkylation conditions with a catalyst selected from the group consisting of sulfuric acid, chlorosulfonic acid, fiuorosulfonic acid, aluminum chloride, and aluminum bromide in the presence of a small amount of free hydrogen effective to overcome the effect of said dioleiin on acid consumption.

References Cited in the file of this patent UNITED STATES PATENTS 2,786,878 Arundale et a1 Mar. 26, 1957 3,046,316 Gudelis July 24, 1962 3,050,456 Melchin Aug. 21, 1962 3,098,882 Arnold July 23, 1963 3,108,947 Stijntjes Oct. 29, 1963 FOREIGN PATENTS 586,848 Great Britain Apr. 2, 1947 

1. A METHOD OF DECREASING ACID CONSUMPTION IN THE SULFURIC ACID CATALYZED ALKYLATION OF AN ISOPARAFFIN WITH A MONOOLEFIN CONTAMINATED WITH A SMALL AMOUNT OF A DIOLEFIN WHICH COMPRISES CONDUCTING SAID ALKYLATION UNDER ALKYLATION CONDITIONS IN THE PRESENCE OF A SMALL AMOUNT OF FREE HYDROGEN EFFECTIVE TO OVERCOME THE EFFECT OF SAID DIOLEFIN ON ACID CONSUMPTION.
 15. A METHOD OF TREATING A HYDROCARBON FRACTION CONTAMINATED WITH A CONTAMINATING AMOUNT OF A DIOLEFIN WHICH COMPRISES CONTACTING SAID HYDROCARBON FRACTION 